Creating Connectors and Cables: Ensuring Signal Quality and Precision
In the world of high-speed designs, maintaining signal integrity is paramount to ensure data transmission is accurate and reliable. Keven Coates, Senior Electrical Engineer at Fluidity Technologies, offers valuable insights to achieve this goal.
Coates recommends that cables and connectors in high-speed designs should have uniform impedance throughout their length. This is achieved by dispersing grounds in between signals wherever possible, creating a stable reference and minimal inductance return path for high-speed signals.
In a 20-conductor cable and connector with a single reference plane, not all signals have access to the return path. If a signal cannot reach a return path, it is not shielded from EMI. To avoid this issue, every signal on the cable must have access to a return path.
Crosstalk occurs when signals take the path of another signal to return. To prevent this, controlled impedance routing is essential, with precise trace widths and spacing, especially for differential pairs, keeping them symmetrical and maintaining constant spacing to achieve the target differential impedance.
Coates also emphasizes the importance of EMI mitigation. Designs should incorporate solid ground planes, shielding, adequate spacing between adjacent signal traces, and secure connector types to prevent radiated emissions and susceptibility to external noise sources.
In addition to these practices, Coates advises close collaboration between electrical and PCB design teams, keeping signal routing as short and direct as possible, and creating clear assembly documentation to support ongoing signal quality.
Coates brings 28 years of industry experience to Fluidity Technologies, where he is currently working on the development of flying vehicles such as multirotor and eVTOL (electric vehicle take-off and landing). To learn more about Fluidity Technologies' capabilities, visit their design service page.
By following these best practices, signals can propagate with minimal distortion, noise, and EMI, which is critical as data rates reach into multi-gigabit and even terabit per second ranges, where rise times are on the order of tens of picoseconds.
- In high-speed data-and-cloud-computing applications, controlled impedance technology is crucial for maintaining signal integrity, as it allows for uniform impedance throughout the length of cables and connectors, creating a stable reference and minimal inductance return path for high-speed signals.
- To prevent crosstalk and ensure accurate data transmission at rates reaching multi-gigabit and even terabit per second, it's essential to implement controlled impedance routing, precision trace widths, and spacing, especially for differential pairs, in addition to collaborating closely between electrical and PCB design teams, and mitigating EMI through practices such as solid ground planes, shielding, and secure connector types.
